On his arrival he was warmly welcomed by Louis, whom he easily induced to accompany him on his return to the seat of war; for although in his despatches Richelieu had affected to attach an immense importance to the conquest of Pignerol, he was aware that the honour of the French nation must be compromised should her armies be thus checked at the very commencement of the expedition, and he consequently urged the King at once to possess himself of the Duchy of Savoy; an undertaking which presented so little difficulty that its success was certain. In vain did Marie de Medicis represent the injury which Louis must, by such an enterprise, inflict upon his sister; the project flattered the vanity of the King, and accordingly on the 14th of May the vanguard of the French army entered the Duchy, and before the middle of the ensuing month the whole of Savoy, with the exception of Montmelian, was in the possession of his troops. This puny triumph was, however, counterbalanced and outweighed by the disasters at Casal and Mantua, the former of which, from the failure of provisions and reinforcements, fell into the hands of Spinola; while the latter, after having had twenty-five thousand of its inhabitants carried off by the plague, was ultimately lost through treason, and delivered over to pillage by the Imperialist generals. From Savoy the Cardinal endeavoured to induce Louis to advance into the district of Maurienne, but from this project he was strongly dissuaded by the Queen-mother, who had, during the campaign in Savoy, remained at Lyons with Anne of Austria, Marillac the Keeper of the Seals, and other discontented nobles who were opposed to the war in Italy, and were anxious for peace at any price. Negotiations to that effect were, moreover, pending; and Urban VIII had offered himself as arbitrator through the medium of Jules Mazarin,[133] a young man of twenty-eight years of age, whom he had appointed internuncio for that purpose. The talent and energy displayed by the Papal envoy in a position of so much difficulty enchanted Richelieu, who at once recognized in the juvenile diplomatist a congenial spirit, and he determined to attach him to the interests of France. But even while he did full justice to the precocious ability of Mazarin, the minister nevertheless bitterly complained that the violent measures adopted by the Queen-mother and her party rendered the prospect of a peace impossible; and that they attached too great an importance to the pending negotiations, and overacted their uneasiness on the subject of the King's health, and their terrors of the plague.[134] These arguments sufficed to reassure Louis XIII, who, delighted at his success in Savoy, and intoxicated by the plaudits of his courtiers, was eager to pursue a war from which he hoped to acquire fresh reputation; and accordingly, disregarding the expostulations of the peace party, he advanced to St. Jean-de-Maurienne;